Technical Abstract:
Reducing emissions is essential for minimizing the impact of soil fumigation on the environment. Cost-effective methods (e.g., surface water applications or water seal) are needed to reduce fumigant emissions. We have tested various surface seal methods to reduce emissions of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) from Telone C35 (61% 1,3-D and 35% CP) applications in a sandy loam soil in the San Joaquin Valley, CA. Surface seal treatments included standard high density polyethylene (HDPE) tarp over dry and pre-irrigated soil, virtually impermeable film (VIF) tarp, initial water application immediately following fumigation, and intermittent water applications after fumigation. The VIF and HDPE tarp over dry soil resulted in the lowest and the highest total emission losses, respectively. Intermittent water applications reduced 1,3-D and CP emissions more than HDPE tarp and the initial water application treatment, which delayed emission peaks and also reduced total emissions as effectively as HDPE tarp over dry soil. The intermittent water applications sometimes resulted in lower soil profile fumigant concentrations, which raises concerns about fumigation efficacy. These results suggest that an appropriate amount of water is required for achieving maximum emission reduction while achieving adequate fumigation efficacy. The pre-irrigated soil + HDPE tarp consistently reduced fumigant emissions effectively and also yielded the highest surface soil temperature that may benefit overall soil pest control.